Device for grinding a group of lens-like quartz resonators



May 30, 1967 M. N- KOGAN ET AL DEVICE FOR GRINDING A GROUP OF LENS-LIKEQUARTZ RESONATORS Filed July 16, 1964 20 FIG. z:

23 F/6.2 F/G. 3

loosely applied on them in United States Patent 3,321,868 DEVICE FORGRENDING A GROUP 0F LENS-LIKE QUARTZ RESONATORS Mark Naumovich Kogan,Prospect Mira 3-v, Apt. 17,

and Sergei Nikelaevich Kibirev, Kornsomolsky Gorodok 8, Apt. 49, both ofOmsk, U.S.S.R.

Filed July 16, 1964, Ser. No. 383,204- 4 Claims. (Cl. 51129) Thisinvention relates to devices for grinding quartz plates and moreparticularly to devices for grinding a group of lens-like quartzresonators.

It is known that the quality factor (Q) of quartz resonators should notbe less than 2- In order to obtain this value of Q it is most favorableto have a double convex or planoconvex lens shape for the quartz plates,because a spherical surface will increase the inductance of the quartzresonators.

However, highly-stable precision quartz resonators of a lens-likedouble-convex or planoconvex shape should have an orientation anglewithin and the thickness in points equally spaced from the plate centershould not exceed :L-l (when the plate diameter is 26 mm. and the spherediameter is 300 mm.) with the plate elipse along the diameter of notmore than 0.02 mm.

Such high requirements of quartz resonators of double convex orplanoconvex shape bring about the necessity to individually finish eachresonator. This is a very complicated, laborious and expensive operationand quite unsuitable for mass production because of low efiiciency.

Attempts were made to grind a group of such resonators for instance, byplacing several quartz plates with adhered resin balls into a lappingdevice (a cup-grinder) with a heated mushroom-shaped holder, the quartzplates being positioned in the cup by changing the orientation of thelatter. On cooling, the holder with the plates was mounted on a grindingmachine spindle whereon it was rotated for grinding.

The tests of such a group grinding method gave no positive results, asin this case it was impossible to obtain uniformly ground surfaces andit was absolutely impossible to check the characteristics of theworkpiece being ground. We have successfully solved the problem ofgrinding a group of precision quartz resonators and have provided apractical embodiment for such grinding.

It is now possible to accomplish a very productive, mechanized andprecise group grinding of planoconvex and double convex quartzresonators with diameters of 10 mm. and more and with radii of curvatureof more than 100 mm. and wherein said resonators are placed in the lapwith pressing devices which are not cemented with the workpieces to beground.

According to a preferred embodiment of the invention, a group of quartzplate blanks are pressed against the grinding cup surface of a freelyrotating lap with a weight the form of a ring-shaped cylinder and a ringsecured thereto; both the plates and the weight are placed together witha central rod in an eccentric opening of a ring holder which is looselyin contact with the lapping surface of the cup and is held in theopening of a fixed adapter fastened to the machine.

It is an object of the present invention to provide a device whichensures precise spherical shape of one surface of each group of thequartz plate blanks placed into said device by means of grinding.

It is another object of the present invention to provide a device whichensures precise spherical shape for both surfaces of each group of thequartz plate blanks placed into the foregoing device by means ofgrinding.

It is still another object of the invention to provide automaticcorrection of the ground surfaces during the grinding process of theworkpiece.

According to the present invention there is provided a device forgrinding quartz resonators of a lenslike double convex or plano-convexshape comprising a lap in the form of a cup-grinder and an annularholder loosely placed in the lap for receiving quartz blanks in aneccentrically arranged opening therein, a weight in the form of aring-shaped cylinder being secured to the holder and bearing via a lowerannular part upon the blanks to press the same against the grindingsurface of the lap, a central lap rod being received in the holder andloosely resting on the grinding surface of the cup to prevent the blanksfrom shifting towards the center of the opening.

The annular holder itself is located in the opening of a fixed adaptersecured on a bracket.

It is preferable to make the lap out of a soft metal (for instance,bronze) whereas the annular holder and the central rod placed thereinmay be made out of steel. This will make it possible to improve lappingof the grinding surface and eliminate the need to individually correctthe lap cup.

An embodiment of the invention and its operation and advantages will bedescribed in the following description with reference to theaccompanying drawing, in which:

FIG. 1 is a side sectional view of a device for grinding a group ofquartz resonators;

FIG. 2 shows a replaceable part of the device which is used formanufacturing lens-like quartz resonators of a planoconvex shape; and

FIG. 3 shows a replaceable part of the device which is used formanufacturing double convex-shaped resonators from plano-convex-shapedquartz resonators.

In the drawing there is shown a rotary vertical spindle l of a grindingmachine (not shown in the drawing) on which is secured a lap 2 with aconcave spherical grinding surface 3 facing upwards.

The radius of the sphere of surface 3 is equal to the radius of thesphere of the quartz resonator surface. Due to the design features ofthe other parts in the device, the sphere radius is not less than mm.

In the cup of the lap is loosely placed an eccentric annular holder 4,the lower surface 5 thereof being of a convex-spherical shape of thesame radius, as that of surface 3.

Reference numbers 6 and '7 designate the axis of symmetry of holder 4,and reference numbers :8 and 9 mark the symmetry axis of the holderopening.

It is apparent from FIG. 1 that the holder opening is arrangedeccentrically relative to outer cylindrical surface Ill of the holder.

In the opening of holder 4- is a Weight located in the form of anannular cylinder 11 with a lower annular part 13 secured to the cylinderwith screws 12.

Central rod 14- is loosely inserted into the opening of cylinder 11. Rod14 rests on the spherical surface 3; its lower face surface 15 has acorresponding spherical shape. Workpieces or blanks l6 (i.e. roundquartz plate blanks) are arranged in the annular cavity of holder 4under annular part 13 in such a quantity as can be arranged in onelayer.

Rod 14 prevents dislodgement of blanks it from under weight H whichpresses the blanks, through lower part 13, against grinding surface 3.The surface of part 13 is of a cone shape. The cone angle is dependenton the sphere radius, as well as on the diameter and quantity of theplate blanks to be simultaneously ground so that the plates are in closecontact with the cone of part 13.

Cylinder 11 with its lower cone part 13 (as; shown separately in FIG. 2)is designed for maufacturing planoconvex resonators.

In order to decrease frictional resistance resulting from sliding ofblank 16 relative to part 13 and to reduce the grinding effect .betweenthe surfaces of these parts, part 13 is made out of a material with verylittle abrasive property, such as for example, polytetrafluoroethylene.

The annular holder 4- is located in the opening of an adapter 17 securedon machine bracket 18. For controlling grinding process, the adapter maybe moved together with the bracket, in the vertical direction (as shownin the drawing by arrows l9), and in the horizontal direction (as shownin the drawing by arrows The quantity of round blanks l6 placed underannular part 13 should preferably be not less than eight in order todistribute more advantageously the pressure on the blanks.

Grinding of the lower surfaces of blanks 16 is carried out in thefollowing order.

First, a pressure pump (not shown in the drawing) is activated todeliver to the cup of lap 2 a conventional grinding suspension used forgrinding quartz plates. When lap 2 rotates, adhesion forces make annularholder 4 rotate in adapter 17.

Cylinder 11 with lower cone annular part 13 begins rotating as well butwith a slower rotational speed than that of holder 4. Blanks 16 placedunder weight 11 and part 13 start rotating each about its own axis dueto the speed difference at the opposite points on the blank, as well asabout their common axis 8-9 together with cylinder l1 and part 13.

The noncoincidence of axis 945 and axis 7-6 (due to their eccentricity)allows to impart to the blanks some additional motion which provides foruniform grinding of the spherical surface.

When grinding blanks 16, surface 3 of lap cup 2 is automaticallycorrected with surface 15 of rod 14 and holder 4.

The axis of opening 21 in adapter 1'7 is displaced relative to therotation axis of lap 2 by a value which provides maximum rotation speedfor holder 4 and constant projection of the holder beyond the lap cup.

Upon grinding one surface of blank 16, cylinder 11 and part 13 (FIG. 2)are removed from holder 4. Then blanks 16 (now already resonators of aplanoconvex shape) are turned over with the spherical side upright andanother cylinder (as shown in FIG. 3) is inserted into the opening ofholder 4.

Lower annular portion 22 of this cylinder has a lower concavo-sphericalsurface 23, the sphere radius of which is equal to that of sphere 3 andconsequently, to the radius of the sphere of blanks 16 which are alreadyground and turned over with their convex sides upright.

Then the grinding of the second, now the lower, surface of quartz blanks16 (planoconvex resonators) begins.

As a result of this second grinding, quartz resonators of a lens-likeshape with a double-convex surface are manufactured.

If only one surface of blanks 16 is ground, then a lenslike quartzresonator with a planoconvex surface is produced.

The present invention can be used for manufacturing precision lens-likequartz resonators with a double-convex or planoconvex surface. Saidresonators are employed for frequency stabilization of radio elementsand units.

The device can also be utilized for grinding of lens.

It should be pointed out that the present invention providesmanufacturing of precision quartz resonators and optical lenses having athickness of not more than il r at points equally spaced from the platecenter within the diameter range of from 10 mm. and more, with thesphere radius from mm. and more, with a frequency diversity of not morethan 3 kc. in a group.

Although the present invention is described in accordance with itspreferable embodiment, it is apparent that alterations and modificationsmay be made therein by those skilled in the art without departing fromthe spirit and scope of the invention as set forth in the appendedclaims.

We claim as our invention:

ll. A device for grinding blanks to form quartz resonators, said devicecomprising a rotatable lap having a concave-spherical grinding surfacefacing upwards, a cylindrical resonator blank holder provided with aneccentrically arranged opening, said resonator having a lowerconvex-spherical surface in contact with the lap surface, a replaceablecylinder loosely placed in the eccentric opening of the holder forpressing blanks against the lap surface, an annular part having a lowerconical surface, said annular part being fastened to the cylinder andadapted for resting on the blanks to urge the same against the lapsurface, said cylinder having a bore therein, a cylindrical rod mountedin the bore of the cylinder and provided with a lower convex-sphericalsurface, said rod restricting the blanks to a position beneath theconical surface of said annular part, and an adapter having an openingreceiving the blank holder, said adapter being adjustable vertically andhorizontally to control the adapter position and that of the holder.

2. A device as claimed in claim 1 wherein said annular part isconstituted of a material of low abrasive property.

3. A device as claimed in claim 1 wherein the opening of said adapter iseccentric with respect to the axisof rotation of the lap, said adapterprojecting beyond the lap.

4. A device as claimed in claim 1 comprising a second cylinder forreplacement of the first, and an annular part secured to the lattercylinder having a concave-spherical surface for accommodation of theconvex surface of ground blanks whereby a double convex surface can beformed on said blanks.

References Cited UNITED STATES PATENTS HAROLD D. WHITEHEAD, PrimaryExaminer.

1. A DEVICE FOR GRINDING BLANKS TO FORM QUARTZ RESONATORS,SAID DEVICECOMPRISING A ROTATABLE LAP HAVING A CONCAVE-SPHERICAL GRINDING SURFACEFACING UPWARDS, A CYLINDRICAL RESONATOR BLANK HOLDER PROVIDED WITH ANECCENTRICALLY ARRANGED OPENING, SAID RESONATOR HAVING A LOWERCONVEX-SPHERICAL SURFACE IN CONTACT WITH THE LAP SURFACE, A REPLACEABLECYLINDER LOOSELY PLACAED IN THE ECCENTRIC OPENING OF THE HOLDER FORPRESSING BLANKS AGAINST THE LAP SURFACE, AN ANNULAR PART HAVING A LOWERCONICAL SURFACE, SAID ANNULAR PART BEING FASTENED TO THE CYLINDER ANDADAPTED FOR RESTING ON THE BLANKS TO URGE THE SAME AGAINST THE LAPSURFACE, SAID CYLINDER HAVING A BORE THEREIN, A CYLINDRICAL ROD MOUNTEDIN THE BORE OF THE CYLINDER AND PROVIDED WITH